RFCs: checkbox for reading the docs

Author: ewels

.github/ISSUE_TEMPLATE/new_rfc.yml

@@ -6,6 +6,11 @@ projects: nf-core/127
 assignees:
   - nf-core/core
 body:
+  - type: checkbox
+    label: Have you read the [RFC / Proposal documentation](https://nf-co.re/docs/contributing/project_proposals)?
+    options:
+        - label: Yes, I have read and understood the docs
+          required: true
   - type: textarea
     attributes:
       label: Summary